1. Field of the Invention
Present invention relates to a multi-quality electric power supply apparatus for supplying the electric power of the quality according to demand of various loads.
2. Related Art Statement
Electric energy is used widely because of easy handling, and now, the electric power supply is performed with very high quality. However, there are various loads, such as heating application etc, in which the quality is not demanded, but low-cost is required, and such as computer or the like, in which instantaneous voltage dip and service interruption cannot be allowed. Moreover, in recent years, according to spread of distributed electricity generating devices such as co-generation, micro turbines, photovoltaic generation and wind power generation, etc, and to tendency to deregulation in power generation, power transmission and distribution systems, the photovoltaic generation device or the like is set up in the home, and, in addition, the regenerative electric power from the distributed generation device comes to be supplied to the distribution system.
Therefore, as an idea with a new distribution system, the method of supplying the multi-quality electric power for supplying the electric power of the quality according to demand of load, is proposed from universities.
By the way, when the multi-quality electric power supply is carried out, the cost of the system to execute it becomes a problem. That is, if all routes to the customer from the power plant through the power transmission line and the distribution line, are provided in plural in accordance with the quality, the cost of the system increases extremely, and thus the cost of the electric power will increase accordingly, too.
Moreover, there is a fear of causing the voltage increase of the distribution line according to a reverse-flow and the frequency change in the system according as an increase of the distributed generation device. In addition, due to non-linear load, a harmonic current flows in the system, so that the voltage of the system becomes a tendency of distortion.